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| Date | Speaker | Topic |
|---|
| September 18 |
Clive Tadhunter
(Sheffield) |
Triggering the most
luminous AGN |
| Quasars are among the most luminous objects in the
Universe, and they are
thought to play a key role in controlling the star formation in their host galaxies
via the feedback effect of the powerful outflows that they drive. However, we know surprisingly little about how, when and where quasars are triggered as
galaxies evolve. In this colloquium I will review quasar triggering mechanisms,
and present new results from an optical and far-infrared study of a large sample of
radio galaxies that cast direct light on the quasar triggering issue. The results
demonstrate that radio galaxies are a diverse population. Whereas mergers
are the most likely triggering mechanism for radio galaxies that harbour
luminous, quasar-like AGN, those with less luminous AGN are more likely to be
triggered by secular processes. |
| September 25 |
Adam Deller
(ASTRON) |
mJIVE-20: Learning from the mJy radio sky at mas resolution |
| At
angular resolutions of a few arcseconds, the radio sky has been extensively surveyed, both in
the wide/shallow and narrow/deep regimes. In contrast, VLBI observations with milliarcsecond
resolution have long been confined to extremely limited areas, primarily due to the
computational challenge associated with imaging large fields at such high angular resolution.
Over the last several years, though, widespread adoption of new VLBI correlator technology
enabling "multifield" correlation has revolutionised VLBI surveying, making it possible to
image hundreds of widely-separated sources from a single pointing. In this talk, I will
describe the largest VLBI survey ever undertaken, the mJy Imaging VLBI Exploration at 20 cm
(mJIVE-20). As part of its goal to construct a well-characterised VLBI legacy dataset,
mJIVE-20 has imaged over 20,000 radio sources taken from the FIRST catalog, detecting over
4,000 objects. mJIVE-20 has produced a number of initial science results, including: 1) clear
evidence for evolution in average source compactness with flux density; comparison to the
available SDSS data and considering AGN unification theories offers several possible
explanations for this effect, 2) the detection of several gravitational lenses, and 3)
detection statistics of slowly variable sources. I will conclude by describing other
potential uses of the mJIVE-20 dataset such as mining for compact symmetric objects. |
| October 2 |
Michael Keith
(JBCA, Manchester) |
Gravitational waves, diamond planets, and other fantastic tales from Parkes |
|
(Or, how I learned to have "no worries" and learn to love The Dish).
The direct detection of gravitational waves is one of the most exciting prospects in observational astronomy. Pulsar timing arrays hope to achieve this by measuring correlated changes in the arrival times of pulses from pulsars caused by the quadripolar distortion of space-time as gravitational waves pass over the Earth. To succeed, these experiments require large radio telescopes to obtain precision (~100 ns) measurements of the pulse arrival times of the most stable 'millisecond pulsars' on timescales up to tens of years.
I will talk about two large projects being observed at the 64-m Parkes Radio Telescope in Australia: The Parkes Pulsar Timing Array (PPTA), which is undertaking this gravitational wave experiment, and the High Time Resolution Universe (HTRU) survey, which is the most sensitive survey for millisecond pulsars to date. As well as highlighting some of the exciting results from the HTRU survey, I will also present the best upper limit on the amplitude of the gravitational wave background to date, and discuss the implications of this on the formation of super-massive black holes and the merger of galaxies.
|
October 9
(2:30pm) |
Stephen Barnett
(Glasgow) |
Schuster Colloquium - The enigma of optical momentum |
| It is more than 100 years since the battle began to determine the correct form of the momentum of light inside a material medium. The two principal contenders for the momentum density are those attributed to Abraham and to Minkowski. The work of Minkowski suggests that the momentum of each photon exceeds its value in free space by a factor of the refractive index. Abraham's approach, however, requires that the momentum is less than that in free space by the same factor. Compelling arguments have been proposed for each of the two candidate momenta. A simple application of Newton's first law of motion to the combined system of a medium and a single photon, for example, leads unambiguously to the Abraham form. An equally simple analysis of single or double slit diffraction, however, leads equally powerfully to the Minkowski form. The problem has not been resolved by experiment, moreover, with experiments supporting both candidate momenta being reported. The resolution, of course is that both are correct...
|
October 11 (FRIDAY)
(EXTRA - 2.10pm) |
Marcelle Soares-Santos
(Fermilab) |
Extra seminar - The Dark Energy Survey status, first results and perspectives |
| The Dark Energy Survey (DES) Collaboration will soon begin a 5000 sq. deg. imaging survey of the southern galactic cap using a new 3 sq. deg., 520 Megapixel CCD camera, the Dark Energy Camera (DECam), mounted on the Blanco 4-meter telescope at the Cerro-Tololo Inter-American Observatory. DECam has achieved first-light in September 2012. Commissioning and science verification were successfully finished in February 2013 and the survey proper will begin in September 2013. DES data will be used to place new and tight constraints on the nature of dark energy via the history of the cosmic expansion rate and the growth of large-scale structure, using the four complementary techniques recommended by the Dark Energy Task Force: weak gravitational lensing, galaxy cluster counts, large-scale structure including baryon acoustic oscillations, and Type Ia supernovae. In this talk, the science projections and prospects will be described, together with the status of the project and the first results obtained from the early commissioning and science verification data. |
October 15 (TUESDAY)
(EXTRA - 3.00pm) |
Peter Dewdney
(SKA) |
Extra seminar - The Baseline Design for the SKA |
| TBA |
October 16
(Note time - 3:30pm) |
Victor Debattista
(UCLAN) |
The evolution of disc galaxies |
| I will discuss new results concerning the evolution of disc galaxies on a range of scales. Time permitting, I will discuss the formation of nuclei, the migration of stars across discs and the orientation of discs and halos. |
| October 23 |
Erminia Calabrese
(Oxford) |
Small scale anisotropies from the Atacama Cosmology Telescope |
| The Atacama Cosmology Telescope
has measured the CMB angular power spectra to arcminute scales at frequencies of 148 and 218 GHz, from 3 seasons of
data. At small scales the fluctuations of the primordial CMB
become increasingly obscured by extragalactic and secondary
signals. We use multi-frequency data to characterise CMB and four
late-time astrophysical components: thermal and kinetic SZ,
emission from CIB galaxies, and emission from radio
galaxies. Modeling these foregrounds emission allow us to probe
the primordial CMB down to an angular resolution of 4
arcminutes. The accurate ACT foreground characterization is
moreover extremely useful in cleaning the primary high resolution
CMB measurements from the Planck satellite. |
| October 30 |
— |
Internal Symposium |
| November 1 |
Julian Bautista
(APC Paris) |
Extra seminar - Baryon Acoustic Oscillations in the Lyman-alpha forest of BOSS quasars |
| I will present the first detection of the baryon acoustic oscillations (BAO) peak in the clustering of the intergalactic medium measured using the Lyman-alpha forest of BOSS quasars (Busca et al. 2013, Slosar et al. 2013). The BAO peak is a standard ruler useful to access distances and the expansion rate of the Universe. We report a measurement of H(z = 2.3) = 224 +/- 8 km/s/Mpc, demonstrating the deceleration of the expansion when comparing with galaxy BAO measurements at lower redshifts. This first measurement is a proof of concept of the Lyman-alpha forests as tracer for BAO studies. With easier access to higher redshifts compared to galaxies, Lyman-alpha forests open a large observational window to future surveys. |
November 6
(2:30pm) |
Paola Borri
(Cardiff) |
Schuster Colloquium - Shedding new light on cells with coherent multiphoton microscopy. |
| TBA |
| November 12 |
Clare Chandler
(NRAO) |
Extra seminar - The formation of planetesimals in proto-planetary disks, observed with the Jansky VLA |
| TBA |
| November 13 |
Mikako Matsuura
(UCL) |
Herschel and ALMA find supernovae as dust factories |
| The formation of dust by core-collapse supernovae (CCSNe) is one of the key processes in the chemical and physical evolution of supernova ejecta, with implications for the origin of dust in the interstellar media of galaxies.
The Herschel Space Observatory and the ALMA have provided a unique opportunity to investigate the presence of cool dust in recent CCSNe. Herschel detected broad-band far-infrared emission from SN 1987A in the LMC. In order to fit the observed far-infrared continuum emission, 0.4-0.7 solar masses of cold (T ~ 21 K) dust were estimated to be required (Matsuura et al. 2011). ALMA observations have confirmed that the far-infrared emission is indeed continuum emission from dust grains formed in the supernova ejecta. Our studies show that a significant fraction of the elements synthesised by the supernova have now condensed into dust grains in the ejecta, with implications for our view of the contribution of CCSNe to the dust budgets of galaxies. |
| November 20 |
Jonathan Pritchard
(Imperial College) |
Exploring the dawn of cosmic structure with the
21cm line |
| The first billion years after
the Big Bang is the period where the first stars and galaxies
form yet this period remains one at the frontier of
observations. In this talk, I will discuss new techniques
that promise the possibility of transforming our understanding
of this period. First, I will discuss applications of radio
observations of the redshifted 21 cm line. Observations of the
sky averaged global signal with single dipole experiments and
measurements of fluctuations with interferometers could offer
new insights into reionization and early X-ray and UV emission
of the first galaxies. After discussing the theory, I'll
finish by summarising the state of 21cm experiments and
prospects for the future. |
| November 27 |
Valery Nakariakov
(Warwick) |
Magnetohydrodynamic seismology of the solar corona in the era of SDO |
| The study of wave processes in the plasma of the solar corona is one of the most rapidly developing branches of solar physics. Wave and oscillatory phenomena with periods ranging from a few seconds to several tens of minutes are confidently detected in various observational bands, from radio to gamma-rays, and interpreted as MHD modes of coronal plasma non-uniformities . The talk presents a comprehensive review of recent achievements in the field, including the discovery of the decay-less regime of standing kink oscillations of coronal loops, observational and theoretical studies of sausage modes, progress in understanding of physical mechanisms for the excitation of various MHD modes, and identification of standing longitudinal oscillations in solar and stellar flares. |
December 4
(2.30pm) |
Robert Braun
(SKA) |
Schuster Colloquium - The Square Kilometer Array. |
| The Square Kilometre Array will be the world's largest and most sensitive radio telescope. The total collecting area will be approximately one square kilometre giving 50 times the sensitivity, and 10 000 times the survey speed, of the best current-day telescopes. The SKA will be built in Southern Africa and in Australia. Thousands of receptors will extend to distances of up to 3 000 km from the central regions. The SKA will address fundamental unanswered questions about our Universe including how the first stars and galaxies formed after the big bang, how dark energy is accelerating the expansion of the Universe, the role of magnetism in the cosmos, the nature of gravity, and the search for life beyond Earth. The target construction cost is €1,500 million and construction of Phase one of the SKA is scheduled to start in 2018. The SKA Organisation, with its headquarters in Manchester UK, was established in December 2011 as a not-for-profit company in order to formalise relationships between the international partners and centralise the leadership of the project.
|
December 6
(12.00 midday) |
Slava Lukin
(NRL) |
Extra seminar - Study of magnetic reconnection in the fluid regime: the variety of environments and outcomes. |
| The global evolution of magnetized plasma systems where magnetic reconnection is known to play a critical role is often well-described by fluid-based approximations of the plasma dynamics. This holds true for most laboratory, solar, and astrophysical scale plasmas where the global system sizes are much greater that the spatial scales on which the magnetic field topology is allowed to change by breaking and reconnecting individual magnetic field lines. This talk will focus on some of the key questions in the study of the magnetic reconnection phenomenon: How do magnetic field lines decouple from the plasma fluid? and How can these small-scale mechanisms responsible for the field-line reconnection affect the macroscopic dynamics of the global system? What we know, what we think we know, and what we definitely don't know will be highlighted by examining magnetic reconnection in a number of different plasma parameter regimes and fluid-based numerical models with different decoupling mechanisms. |
| December 6 |
Benjamin Racine
(APC Paris) |
Extra seminar - Non-Gaussianity with Planck: fNL and the smoothed bispectrum using the binned bispectrum estimator |
| Primordial Non-Gaussianities are a probe of extreme physics during first instants of the Universe, especially useful for discriminating between different inflationary models. The Planck satellite, an ESA mission dedicated to the measurement of CMB temperature and polarization fluctuations, released its first results this year. With its bolometric technology, its unprecedented precision enables renewed study of non-Gaussianity in the CMB. The non-linear parameter fNL is the most popular way of characterizing it, but in the lack of a theoretical prior, the bispectrum itself provides more information. I will present an overview of the Planck non-gaussianity results (Planck 2013 Results XXIV), focusing specially on the binned bispectrum estimator (Bucher et al. 2009), which provides a nearly optimal estimation of fNL, and allows non-parametric study of the smoothed bispectral signal. |
| December 11 |
Christoph Mordasini
(MPIA, Heidelberg) |
Planetary population synthesis and the planetary mass-radius relationship |
| The last few years have seen a tremendous increase of observational data regarding the properties of extrasolar planets. High precision radial velocity and transit observations have yielded large datasets which are important to improve our understanding of planet formation and evolution. But also other techniques like microlensing have started to contribute information regarding other basic properties of the extrasolar planets.
Bringing all these different dataset into one coherent picture to improve our theoretical understanding is challenging, as each technique constrains a different aspect of the formation and evolution process. I will present planetary population synthesis as a young and useful method in this context, making many comparisons of theoretical results and observational data possible.
For the synthesis, we use a planetary formation model that is based on the core accretion paradigm, but includes also disk migration and disk evolution. By varying the initial conditions of the model according to observed distributions of properties of protoplanetary disk (e.g. disk mass or lifetime) we synthesize planetary populations.
As an application, I will show comparisons with transit observations, addressing the synthetic and the observed radius distribution and the planetary mass-radius relationship. We find that the latter can only be reproduced if strongly reduced grain opacities are assumed during the formation process, establishing an interesting link between microphysical processes like grain growth during formation and observable quantities nowadays. |
December 12
(3.30pm) |
Anna Scaife
(Southampton) |
Extra seminar - High Energy Processes in Low Mass YSOs |
| Although non-thermal emission is a standard observational tool for examining jets from AGN, in the lower energy analogue of proto-stellar jets thermal emission has historically been assumed to be the dominant (if not sole) mechanism. However, this has been called into question by the recent detection of highly linearly polarized emission in a jet from the young high mass star HH 80-81. Many features of the observed polarisation in HH 80-81 are similar to those seen in more highly energetic AGN jets, strengthening the argument that certain jet formation characteristics span huge mass and energy scales. Linear polarisation has yet to be discovered in low mass protostellar jets, but here I will show recent results which indicate that non-thermal processes are also present in such systems and discuss the potential implications of these data. |
| January 29 |
Chris Messenger
(Glasgow) |
Gravitational wave detection: Prospects and future possibilities |
| The advanced generation of ground-based gravitational wave detectors will soon become operational. Compared to the initial generation they will increase our sensitive distance by a factor of 10 (to ~200Mpc) and hence increase the sensitive volume to compact binary coalescences and their event rate by 3 orders of magnitude. This sensitivity increase coupled with current predictions for the astrophysical populations of binary neutron stars give us an estimated realistic detection rate of 0.4-400 per year. I will provide a review of the sensitivities and results obtained with the initial detectors and then describe the issues of most relevance for detection in the next few years. I will conclude by discussing the potential for performing cosmological measurements using gravitational wave standard sirens, an area of gravitational wave research of specific interest to myself. |
| February 5 |
Jenny Nelson
(Imperial) |
Schuster Colloquium - Molecular Electronic Materials for use in Solar Cells |
| The application of molecular semiconductor materials to optoelectronics presents both an opportunity, in terms of the vast range of material properties and applications that can be achieved through chemical synthesis, and a challenge, in relating optoelectronic properties of the resulting devices to the chemical structure and microstructure of the materials. The challenge is complicated by the intrinsic disorder in electronic energy levels, the structural heterogeneity of organic semiconductors and their dielectric properties.
In this seminar, we focus on the application of these materials to photovoltaic energy conversion, where the prospect of low-cost solar panel manufacture using printing or coating has attracted intense interest. We discuss how the molecular nature of the materials influences the processes of light harvesting and photocurrent generation in a solar cell. We show how a range of electronic, spectroscopic and structural measurement techniques, together with molecular and device modelling, can be used to relate the properties of the materials to their performance in solar cells. Finally we address the factors that limit power conversion efficiency in such devices.
|
Thursday February 6
(1.00pm) |
Mark Allen
(CDS, Strasbourg) |
Extra seminar - The CDS and the Virtual Observatory Enabling Science |
| TBA |
| February 12 |
Paul Crowther
(Sheffield) |
The most massive stars in the Local Universe |
| The lower limit to the mass of stars is well defined, while the upper limit remains controversial. I shall summarise evidence in support of the currently accepted limit, and present VLT and HST-based studies of the brightest members of young, nearby star clusters to argue for a higher limit. Consideration is given to issues of binary using a variety of methods, while star cluster simulations are presented which argue for an upper limit close to 300 solar masses. The wider significance of the upper mass limit is discussed both from the perspective of the integrated properties of star clusters (including new spatially resolved HST/STIS UV/optical spectroscopy of the R136 star cluster in the LMC Tarantula nebula) and the possibility that pair-instability supernovae exist in the Local Universe. |
| February 19 |
Robert Braun
(SKA) |
Near-Field
Cosmology |
| Two new tools for understanding the distribution and cosmic evolution of atomic and ionised gas are described that
rely on recent deep imaging of the neutral hydrogen disks of nearby galaxies: 1) documenting cosmic evolution of the neutral hydrogen distribution function via sub-100pc imaging of the HI distributions
and 2) probing the dark baryons in galaxy groups using ram pressure interactions with the intergalactic medium. |
| February 26 |
Jean-Luc Starck
(CEA, Saclay) |
Joint CMB map reconstruction from
WMAP-9yr and Planck-PR1 data |
| We present the first CMB map reconstructed from both WMAP and Planck datasets. Using recent statistical tools based on sparsity, we show that the Galactic barrier can be broken down, so that we can have a full sky high quality CMB map, for the first time. In addition, as a result of our novel approach, this high quality map is free of any significant thermal SZ contamination. Finally, we present a new method to reconstruct the primordial power spectrum from WMAP-9yr data. |
| March 5 |
Manda Banerji
(UCL) |
The Dustiest
Quasars in the Universe: Observing the transition from
starburst to AGN |
| I will discuss a new population
of extremely dusty, hyperluminous quasars at redshifts of ~2-3
discovered using new sensitive wide-field infrared surveys
(e.g. UKIDSS, VISTA, WISE). These new quasars are among the most
luminous quasars known with extremely large black-hole masses and
evidence for strong outflows, suggesting we are watching AGN
feedback in action. They are believed to be massive,
hyperluminous starburst galaxies caught in the short-lived
transition process of turning into UV-luminous quasars - a
critical phase in galaxy evolution predicted by simulations but
as yet poorly studied at high redshifts. Despite their extreme
properties, the dusty quasars have been previously unstudied
because bright quasars are typically selected at UV/optical
wavelengths where dust renders the reddest quasars
invisible. Dusty quasars may provide the missing link between
starburst galaxies and UV-bright quasars at high redshifts. I
will discuss the implications of these new quasars for galaxy
formation and coeval galaxy and black-hole growth, present our
ongoing spectroscopic follow-up program to find larger numbers of
them and discuss follow-up observations at X-ray and far
infra-red wavelengths to place the new quasars in context with
other well-studied high redshift galaxy populations. |
| March 12 |
Ian Shipsey
(Oxford) |
|
| TBA |
| March 19 |
Carole Mundell
(LivJMU) |
The Transient Explosive Universe |
| I will describe recent advances in autonomous robotic observation of the instantaneously most luminous objects in the Universe - Gamma Ray Bursts (GRB). In particular, I will present new experiments using novel 'RINGO' optical polarimeters on the 2-m Liverpool Telescope to study the magnetic fields predicted to collimate and accelerate the ultra-relativistic GRB jets. I will discuss the unexpected dearth of bright optical flashes that were expected to be ubiquitous in the early optical afterglow, produced by the so-called reverse shock, and introduce a new model that predicts flares at radio and mm wavelengths instead. I will finish with a look to the future, describing new experiments to (a) characterise the transient optical sky down to the LSST bright limit, (b) search for the optical counterparts of Fast Radio Bursts as well as the rapid followup of new transient sources, such as Tidal Disruption Events, that will be identified by the recently lauched GAIA satellite (c) the multiwavelength horizon going into the next decade. |
| April 2 |
Iain McDonald
(Manchester) |
Metal-poor stars: tracers of the Universe's chemical evolution |
| We are stardust: 90% of our bodies were made in a star, and each atom has a story to tell of its formation. The chemistry of today's Universe is set by the dust and gas lost by previous generations of stars, yet the processes governing mass-loss are very uncertain. I will talk about how today's Universe could vary if we changed mass loss from metal-poor stars within the boundaries of our observational uncertainties and touch upon the consequences for the early and high-redshift Universe. I will talk about how we are working to reduce those uncertainties. This will focus on the results of our recent observational campaigns in dwarf galaxies and globular clusters, concentrating on how the dust and gas ejected from stars changes with stellar metallicity. |
| April 9 |
Jane Greaves
(St Andrews) |
Searching for solar system twins |
| What aspects of the solar system
are important for the habitability of the Earth? Many suggestions
have been made, from the activity levels of the Sun to the
(chance) presence of a large Moon. I will discuss the range of
possible planetary system architectures, and in particular the
link between planets and debris discs. An exploration of some of
the Sun's nearest neighbours shows that their planetary systems
differ radically from ours in both time and space. Thus, the
search for exo-life needs to explore what (to us) are extreme
conditions. The sub-title of this talk should probably be: 'Main
sequence stars - not nearly as dull as you thought!'. |
| April 23 |
Chris Hales
(NRAO) |
The nature of faint polarized radio sources |
| A number of studies have reported an anti-correlation between fractional linear polarization and total intensity flux density for extragalactic 1.4 GHz sources; faint sources were found to be more highly polarized. As a result, the differential number-counts of polarized sub-millijansky sources have been observed to flatten to levels greater than expected from population modeling. This possibly indicates more ordered magnetic fields in faint sources or the emergence of an unexpected population. In this talk I will investigate the nature of faint polarized radio sources by presenting new results from a deep survey with the Australia Telescope Compact Array. I will describe tools developed to analyze the data, and present the resulting statistics of the faint polarized sky including number-counts and fractional polarization properties. To complement these results, I will summarize an emerging picture in the literature that updates the orientation-based interpretation of asymmetric depolarization in double radio sources and provides a link to probing AGN feedback. |
| April 30 |
Benjamin Joachimi
(UCL) |
Errors of errors and systematics of systematics |
| On-going and forthcoming
spectroscopic and imaging surveys provide increasingly large and
rich datasets for cosmology. To optimally exploit them, we need
to improve our understanding of all steps in the data analysis
methodology, and quantify their accuracy. I am going to present
recent advancements in two areas that are of interest
particularly for weak lensing measurements, the estimation of
error covariance matrices and the intrinsic alignment of
galaxies. While conceived as necessary evils to be dealt with on
the path to precision cosmology, I will detail that both subjects
have revealed interesting insights and fruitful links to pure
statistics and galaxy evolution, respectively. |
May 7
2.30pm |
Subir Sarkar
(Oxford) |
|
| TBA |
May 7
4pm |
Daniel Mortlock
(Imperial) |
Bayesian model comparison in astronomy and cosmology |
| Bayesian inference provides a
self-consistent method of model comparison, provided that i)
there are at least two models under consideration and ii) all the
models in question have fully-specified and proper parameter
priors. Unfortunately, these requirements are not always
satisfied in astronomy and cosmology: despite the existence of
exquisitely-characterised measurements and quantitative physical
models (i.e., sufficient to compute a believable likelihood),
these models generally have parameters without well-motivated
priors, making completely rigorous model comparison a formal
impossibility. Still, huge advances have been made in cosmology,
in particular, in the last few decades, implying that model
comparison (and testing) is possible in practice even without
fully specified priors. I will discuss the above principles and
then illustrate some test cases of varying rigour, outlining some
schemes for formalising heuristic approaches to model testing
within a Bayesian framework. |
May 13
(TUESDAY) |
Ue-Li Pen
(CITA) |
Special seminar - Detecting Neutrinos with peculiar flows |
| We apply the Tseliakhovich-Hirata effect to predict the CDM-neutrino background relative flow, which is comparable to the neutrino thermal velocity of several hundred km/sec. We show that this results in a potentially observable lensing dipole, which is robust from systematics. |
May 15
(THURSDAY) |
Tim de Zeeuw
(ESO) |
Special seminar - ESO: Present and Future |
| ESO is an intergovernmental organization for astronomy founded in 1962 by five countries. It currently has 14 Member States in Europe with Brazil poised to join as soon as the Accession Agreement has been ratified. Together these countries represent approximately 30 percent of the world's astronomers. ESO operates optical/infrared observatories on La Silla and Paranal in Chile, partners in the sub- millimeter radio observatories APEX and ALMA on Chajnantor and has started construction of the Extremely Large Telescope on Armazones.
La Silla hosts experiments, robotic and national telescopes as well as the NTT and the venerable 3.6m telescope. The former had a key role in the discovery of the accelerating expansion of the Universe and the latter hosts the ultra-stable spectrograph HARPS which is responsible for the discovery of nearly two-thirds of all confirmed exoplanets with masses below that of Neptune. On Paranal the four 8.2m units of the Very Large Telescope, the Interferometer and the survey telescopes VISTA and VST together constitute an integrated system which supports 16 powerful facility instruments, including adaptive-optics-assisted imagers and integral-field spectrographs, with half a dozen more on the way and the Extremely Large Telescope with its suite of instruments to be added in about ten years time. Scientific highlights include the characterisation of the supermassive black hole in the Galactic Centre, the first image of an exoplanet, studies of gamma-ray bursts enabled by the Rapid Response Mode and milliarcsec imaging of evolved stars and active galactic nuclei. The single dish APEX antenna, equipped with spectrometers and wide-field cameras, contributes strongly to the study of high-redshift galaxies and of star- and planet-formation. Early Science results obtained with the ALMA interferometer already demonstrate its tremendous potential for observations of the cold Universe.
The talk will outline the development of ESO, summarize the current program and consider new opportunities for the coming decades. |
| May 21 |
Keith Grainge
(Manchester) |
AMI follow up of the Planck cluster catalog |
| The Planck satellite has performed the first all sky galaxy cluster survey since that made by the ROSAT X-ray telescope. It has identified the clusters through the Sunyaev-Zel'dovich (SZ) effect, a secondary anisotropy on the CMB. The AMI telescope has followed up a subsample of 123 clusters from this catalogue at higher angular resolution, detecting 99 of them. We analyse the data using the "universal" pressure profile of the Generalised Navarro, Frenk and White (GNFW) model. Y_tot values as measured by AMI are biased downwards with respect to the Planck constraints and we investigate how this could be resolved by deviation of the GNFW model from the "universal" values.
|
| May 28 |
Katherine Joy
(Manchester) |
Unravelling the impact history of the Moon |
| TBA |
| June 4 |
David Kipping
(CfA, Harvard) |
The Hunt
for Exomoons with Kepler (HEK) Project |
| The discovery of moons around extrasolar planets presents an outstanding challenge in modern astronomy with the potential to reveal deep insights into formation models. Precise photometric time series from space telescopes, such as Kepler, are sensitive to transiting planets as small as the Earth and thus may be sensitive to large exomoons too. I discuss the techniques which can be deployed to betray the presence of an exomoon and the expected sensitivities. Using these methods, the Hunt for Exomoons with Kepler (HEK) project has been searching for signals over the past two years. During these teething years, we have demonstrated the capacity to detect Earth-Moon mass ratio systems in roughly 1 in 6 cases, and Pluto-Charon mass-ratios for 1 in 3. I'll discuss the exciting ancillary science which has culminated from our search and the outlook for the future.
|
| June 25 |
Clem Pryke
(Minnesota) |
Special seminar - BICEP2:
Detection of B-mode polarization on degree angular scales |
| We report results from the BICEP2
experiment, a Cosmic Microwave Background (CMB) polarimeter
specifically designed to search for the signal of inflationary
gravitational waves in the B-mode power spectrum around l=80. The
telescope comprised a 26 cm aperture all-cold refracting optical
system equipped with a focal plane of 512 antenna coupled
transition edge sensor (TES) 150 GHz bolometers each with
temperature sensitivity of approx. 300 microK-sqrt(s). BICEP2 observed
from the South Pole for three seasons from 2010 to 2012. A
low-foreground region of sky with an effective area of 380 square
degrees was observed to a depth of 87 nK-degrees in Stokes Q and
U. In this paper we describe the observations, data reduction,
maps, simulations and results. We find an excess of B-mode power
over the base lensed-LCDM expectation in the range 30 < l < 150,
inconsistent with the null hypothesis at a significance of
>5sigma. Through jackknife tests and simulations based on detailed
calibration measurements we show that systematic contamination is
much smaller than the observed excess. We also estimate potential
foreground signals and find that available models predict these to
be considerably smaller than the observed signal. These foreground
models possess no significant cross-correlation with our
maps. Additionally, cross-correlating BICEP2 against 100 GHz maps
from the BICEP1 experiment, the excess signal is confirmed with 3sigma
significance and its spectral index is found to be consistent with
that of the CMB, disfavoring synchrotron or dust at 2.3sigma and 2.2sigma,
respectively. The observed B-mode power spectrum is well-fit by a
lensed-LCDM + tensor theoretical model with tensor/scalar ratio
r=0.20+0.07-0.05, with r=0 disfavored at 7.0sigma. Subtracting the
best available estimate for foreground dust modifies the
likelihood slightly so that r=0 is disfavored at 5.9sigma. |
| July 23 |
Richard Shaw
(CITA/Toronto) |
Special seminar - The Canadian Hydrogen Intensity Mapping Experiment (CHIME) |
| TBA |
